Syncope is a medical term for fainting and occurs as a result of a reduction in blood flow and oxygen to the brain. Various types of syncope exist and the severity of each may vary. Neurocardiogenic syncope is a common type of syncope and is often referred to as vasovagal syncope. Neurocardiogenic syncopal episodes generally relate to problems with both the heart and the nervous system. For example, the sight of blood or extreme emotional distress may trigger a neurocardiogenic syncopal episode that causes your heart rate and blood pressure to drop suddenly. Orthostatic hypotension is another type of syncope that may be caused by a sudden drop in blood pressure induced by a change in posture—position, such as when an individual stands upright. Both neurocardiogenic syncope and orthostatic hypotension can are typically harmless and require no treatment. On the other hand, cardiogenic syncope is a more serious type of syncope because, while it can be related to other serious cardiac causes, it generally is related to cardiac arrhythmias (e.g., abnormal heart rhythms) In particular, a syncopal episode that is cardiogenic is generally indicative of a more serious underlying heart problem that requires immediate attention.
Syncopal episodes are intermittent in nature and commonly characterized as a temporary loss of consciousness with a fast onset, short duration, and spontaneous recovery. This makes it difficult to diagnose syncope, which requires a diagnostic workup including various forms of physiological information obtained through, for example, electrocardiogram (ECG) monitoring and blood pressure monitoring, among other things. Due to the intermittent nature of syncope, physiological information at the onset of a syncopal episode useful in a diagnosis is often not available. In addition, collecting this information following a syncopal episode is highly invasive and disruptive to a patient's day-to-day activities. Consequently, syncope of unknown etiology is very common and often misdiagnosed.
It would therefore be desirable to provide a system and method of detecting physiological changes associated with undiagnosed symptomatic events such as syncope in a non-invasive manner.